UI UINavigationController导航控制器

<span style="font-size:18px;">AppDelegate.m</span>

<span style="font-size:18px;">    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];    // Override point for customization after application launch.    Root_ViewController *rootVC=[[Root_ViewController alloc]init];        UINavigationController *nav=[[UINavigationController alloc]initWithRootViewController:rootVC];    //设置返回按钮的颜色    nav.navigationBar.tintColor=[UIColor magentaColor];    //设置导航条的颜色//    nav.navigationBar.barTintColor=[UIColor yellowColor];    //设置导航条navigationBar是否透明,默认是YES    nav.navigationBar.translucent=YES;    //设置navigationBar的样式    nav.navigationBar.barStyle=UIBarStyleBlack;    //设置navigationBar的背景图片    [nav.navigationBar setBackgroundImage:[UIImage imageNamed:@"1.png"] forBarMetrics:UIBarMetricsDefault];    self.window.rootViewController=nav;    [rootVC release];    [nav release];            self.window.backgroundColor = [UIColor whiteColor];    [self.window makeKeyAndVisible];    return YES;                /*     UINavigationController是导航视图控制器，负责管理具有层次结构的视图，是管理控制器的控制器，其内容分为两部分：一部分是导航条（navigationBar），另外一部分是内容（contentView）。     导航视图控制器维持了一个栈结构，当push到另外一个viewController时，会执行入栈操作；当返回上一个viewController或返回指定viewController时，会执行出栈操作。     UINavigationBar：导航条，继承自UIView，在MVC中位于V层，负责标题，按钮的显示。其内容也维持了一个栈结构，当push页面时，navigationBar会执行入栈操作，navigationBar会将viewController中的navigationItem属性取出，放入栈中，并显示navigationItem中的相关信息；pop页面时，出栈，将navigationItem从栈中移除，并移除显示的按钮，标题等     UINavigationItem  ：UIViewController的属性，主要用于为navigationBar提供数据，在MVC中，属于M层，类似于一个包裹，内部存放了导航条上显示的按钮，标题等信息。当显示该ViewController时，navigationItem内部信息会被navigationBar显示     UIBarButtonItem：封装了NavigationBar上的按钮信息。在MVC中属于M层（不继承UIView）。NavigationBar在拿到navigationItem后，会将里面的BarButtonItem取出，根据BarButtonItem创建UIButton对象，显示在导航条上。     */        //UINavigationController继承于UIViewController,以栈的⽅式管理所控制的视图控制器,⾄少要有⼀个被管理的视图控制器,这个控制器我们称作,导航控制器的根视图控制器。    //任何继承⾃自UIViewController的类(多态)都可以作为根控制器    //navigationBar—导航条,iOS7之后默认是透明的,iOS7之前默认是不透明的。 navigationBar在透明情况,与contentView会重合⼀部分区域。navigationBar在不透明情况,contentView跟在navigationBar的下⾯。    //navigationBar竖屏下默认⾼度44,横屏下默认⾼度32.</span>

<span style="font-size:18px;">Root_ViewController.m</span>

<span style="font-size:18px;"></span><pre name="code" class="objc">- (void)viewDidLoad{    [super viewDidLoad];    self.view.backgroundColor=[UIColor cyanColor];    //设置navigationItem的文本    self.navigationItem.title=@"首页";    //设置navigationItem的文本视图    UIView *titleView=[[UIView alloc]initWithFrame:CGRectMake(0, 0, 100, 44)];    titleView.backgroundColor=[UIColor magentaColor];    self.navigationItem.titleView=titleView;    [titleView release];        //设置左按钮    UIBarButtonItem *leftBtn=[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemBookmarks target:self action:@selector(leftBtnAction:)];    self.navigationItem.leftBarButtonItem=leftBtn;    [leftBtn release];        //设置右按钮,将图片转换成镂空模式，图片才能显示，否则图片不能正常使用    UIImage *img=[[UIImage imageNamed:@"3.png"]imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];    UIBarButtonItem *rightBtn=[[UIBarButtonItem alloc]initWithImage:img style:UIBarButtonItemStyleBordered target:self action:@selector(rightBtnAction:)];    self.navigationItem.rightBarButtonItem=rightBtn;    [rightBtn release];        UIBarButtonItem *item1=[[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:nil];     UIBarButtonItem *item2=[[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemSave target:self action:nil];     UIBarButtonItem *item3=[[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemReply target:self action:nil];        NSArray *arr=[NSArray arrayWithObjects:item1,item2,item3, nil];    self.navigationItem.leftBarButtonItems=arr;        UIButton *button=[UIButton buttonWithType:UIButtonTypeSystem];    button.frame=CGRectMake(50, 150, 100, 40);    button.backgroundColor=[UIColor redColor];    [button setTitle:@"下一页" forState:UIControlStateNormal];    [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:button];            UILabel *label=[[UILabel alloc]initWithFrame:CGRectMake(50, 100, 100, 50)];    label.backgroundColor=[UIColor whiteColor];    [self.view addSubview:label];    [label release];    self.label=label;        }- (void)leftBtnAction:(UIBarButtonItem*)leftBtn{    NSLog(@"leftBtnAction:");}- (void)rightBtnAction:(UIBarButtonItem *)rightBtn{    NSLog(@"rightBtnAction:");}- (void)buttonAction:(UIButton*)button{    NSLog(@"buttonAction:");    SecondViewController *secondVC=[[SecondViewController alloc]init];    secondVC.str=@"你好";    /*     属性传值：如果从A页面往B页面传值，在B页面中声明属性，在A页面的跳转事件中给B页面的属性赋值          */    //页面切换    [self.navigationController pushViewController:secondVC animated:YES];    [secondVC release];            }- (BOOL)textFieldShouldReturn:(UITextField *)textField{    NSLog(@"%@",textField.text);    self.label.text=textField.text;    return YES;}-(void)viewWillAppear:(BOOL)animated{    //打印navigationController的所有viewControllers    NSLog(@"%@",self.navigationController.viewControllers);}-(void)dealloc{    [_label release];    [super dealloc];}

<span style="font-size:18px;"></span><pre name="code" class="objc"><span style="font-size:18px;">SecondViewController.m</span>

- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view.    self.view.backgroundColor=[UIColor orangeColor];        UIButton *button=[UIButton buttonWithType:UIButtonTypeSystem];    button.frame=CGRectMake(50, 150, 100, 40);    button.backgroundColor=[UIColor redColor];    [button setTitle:@"下一页" forState:UIControlStateNormal];    [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:button];            UILabel *label=[[UILabel alloc]initWithFrame:CGRectMake(50, 100, 100, 50)];    label.text=self.str;    label.font=[UIFont systemFontOfSize:36];    [self.view addSubview:label];    [label release];    self.label=label;        UITextField *textField=[[UITextField alloc]initWithFrame:CGRectMake(100, 200, 200, 50)];    textField.backgroundColor=[UIColor whiteColor];    textField.delegate=[self.navigationController.viewControllers objectAtIndex:0];    [self.view addSubview:textField];    [textField release];    self.textField=textField;    }- (void)buttonAction:(UIButton*)button{    NSLog(@"buttonAction:");    ThirdViewController *thirdVC=[[ThirdViewController alloc]init];    //页面切换    [self.navigationController pushViewController:thirdVC animated:YES];    [thirdVC release];}/* 从后一个页面返回前一个页面不会执行前页面的loadView，viewDidLoad方法，而是执行viewWillAppear方法 因为：loadView和viewDidLoad方法的作用是将视图加载到内存，而从后一个页面返回时，前一个页面已经加载到内存，所以不用再次加载，所以不执行loadView和viewDidLoad方法 */-(void)viewWillAppear:(BOOL)animated{    //打印navigationController的所有viewControllers    NSLog(@"%@",self.navigationController.viewControllers);    //在视图将要显示的时候给label的text赋值    self.label.text=self.str;}-(void)dealloc{    [_str release];    [_label release];    [_textField release];    [super dealloc];}

<span style="font-size:18px;"></span><pre name="code" class="objc"><span style="font-size:18px;">ThirdViewController.m</span>

- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view.        self.view.backgroundColor=[UIColor blueColor];    UIButton *button=[UIButton buttonWithType:UIButtonTypeSystem];    button.frame=CGRectMake(50, 150, 100, 40);    button.backgroundColor=[UIColor redColor];    [button setTitle:@"回到上一页" forState:UIControlStateNormal];    [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:button];        }- (void)buttonAction:(UIButton*)button{    SecondViewController *secondVC=[self.navigationController.viewControllers objectAtIndex:1];    secondVC.str=@"Hello";    ////返回上一页    [self.navigationController popViewControllerAnimated:YES];        //返回到指定下标的//    UIViewController *vc=[self.navigationController.viewControllers objectAtIndex:0];//    [self.navigationController popToViewController:[self.navigationController.viewControllers objectAtIndex:0] animated:YES];    //返回根视图控制器    //[self.navigationController popToRootViewControllerAnimated:YES];}-(void)viewWillAppear:(BOOL)animated{    //打印navigationController的所有viewControllers    NSLog(@"%@",self.navigationController.viewControllers);}